This invention relates to photographic cameras which incorporate automatic electrical systems that operate with periods of relatively high power consumption and of low power consumption. The invention provides a multiple battery supply for powering such electrical systems with high reliability against deficient battery power.
Modern cameras often include electrical systems which set the exposure time, adjust the camera aperture, control the camera shutter, and/or advance the film. In self-developing cameras such electrical systems transport an exposed film unit through processing-initiating spread rolls, and eject it from the camera. The electrical power drain which these systems impose on the camera battery can increase significantly during a camera operating cycle according to the number and the nature of the electrical and electronic functions in the camera. For example, automatic exposure timing and even shutter adjustment typically consume relatively little battery power, whereas the mechanical drive for film advance consumes significantly more power.
A weak camera battery often can drive the electrical system during low power operations, and evidence failure only during a high load or peak power portion of the camera cycle. Thus, a camera with a weak battery can nevertheless commence an operating cycle which starts with low power operations, but will not properly perform the subsequent high power operations such as film advance after exposure. The resultant operating failure and loss of one or more exposures are at the least annoying, and can involve more serious consequences particularly where the user collapses a folding camera which has halted operation in mid-cycle. Further, replacement of a weakened battery while the camera still contains unexposed film can lead to loss of one frame or of all the unexposed film, depending on how the battery is packaged within the camera and relative to the packaging of the film.
The occurrence of these and other battery failure problems are difficult to rule out, because batteries fail due to many factors, including undue dealer storage, improper user care, and exposure to excessive temperature.
Prior art efforts to diminish the battery problem can include low power indicators, and the use of multiple batteries. Thus, two batteries can be placed in series to produce a high voltage useful, for example, for film advance. More often, the batteries are connected electrically in parallel to augment the current supply for high drain operations. The continued parallel connection of a fresh battery with a weak one, however, can diminish the operating life of the fresh battery far below the expected life. U.S. Pat. Nos. 3,853,396 and 3,587,425; and German specification No. 2,457,002 are among the prior art which disclose these and other battery schemes for powering camera operations.
With the foregoing in mind, it is an object of this invention to provide a multiple battery supply for camera electrical systems and which operates with relatively high reliance against failure due to a deficient battery.
Another object of the invention is to provide a novel connection of batteries within a camera whereby the premature aging of one battery does not degrade the performance of another battery. It is also an object to provide a camera system which obtains reliable and long battery operation irrespective of premature aging of another battery of the camera system. Further objects of the invention are to provide an inexpensive and relatively simple system of the above character.
Yet another object of the invention is to provide a novel connection of batteries within a camera wherein a weak battery can drive the camera in a low power drain state, and another battery can selectively drive the camera in a high power drain state.
Other objects of the invention will in part be obvious and will in part appear hereinafter.